A method for evaluating a high-quality reservoir of progressive oolitic limestone while drilling and application thereof

Abstract

The application provides a method for evaluating an aggradational oolitic limestone high-quality reservoir while drilling and application thereof. According to element logging analysis, Ca and Mg elements are used as a carbonate discrimination curve, Si and Fe elements are used as a sandy discrimination curve, and Al and K elements are used as a muddy discrimination curve. A standard layer is selected to carry out sensitive element superposition. According to the curve shape change characteristics, a high-quality reservoir is identified, and an oolitic limestone period is divided, so as to form the method for evaluating the aggradational oolitic limestone high-quality reservoir while drilling. The method can provide a trajectory optimization basis in the process of horizontal well construction, guide drilling construction, and improve the drilling rate of the high-quality reservoir.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, and in particular to a method and application for evaluating high-quality reservoirs in progradational oolitic limestone during drilling. Background Technology

[0002] Oolitic limestone reservoirs are important formations for natural gas exploration and development. Taking the oolitic limestone in northeastern Sichuan as an example, the sedimentary environment is characterized by the shallowest water bodies and the highest energy. The main reservoirs are progradational platform margin oolitic shoals, consisting of multiple overlapping phases of platform margin oolitic shoals. The lithology is entirely oolitic limestone, with weak or underdeveloped dolomization. Most phases of oolitic shoals have poor physical properties, with oolitic mold pores dominating the reservoir space, followed by fractures. Only phases modified by diagenesis, particularly those with quasi-syngenetic dissolution, have relatively well-developed dissolution pores, forming high-quality reservoirs. Drilling has revealed that the vertical thickness of the oolitic limestone reaches tens of meters, but the numerous phases of oolitic shoals and the significant differences in physical properties between different phases make the distribution range of high-quality reservoirs with porosity >4% unclear. Well logging data shows that the gamma ray density (GR) values ​​in oolitic limestone are low, with little difference in values ​​between different oolitic shoals. Resistivity is generally higher than 4000 Ω·m, making it difficult to identify high-quality reservoirs using gamma ray and resistivity-while-drilling techniques. New technical methods are urgently needed to identify high-quality reservoirs from thick oolitic limestone during drilling, guiding horizontal well entry into high-quality reservoirs and extending their reach.

[0003] By applying logging-while-drilling technology, information such as formation GR and resistivity is obtained. Based on the characteristics of the logging-while-drilling curves, high-quality reservoirs are identified. The overall characteristics of high-quality reservoirs are low GR and medium-low resistivity.

[0004] Actual drilling data shows that oolitic limestone has low GR values, generally below 18 API. The values ​​of different oolitic shoals show little difference and cannot be distinguished based on GR alone. Induction logging is generally used for logging while drilling, with a measurement upper limit of 4000 Ω·m, while the resistivity of the formations in the work area is generally higher than 4000 Ω·m.

[0005] By applying elemental logging technology to analyze the chemical composition of rocks, lithology can be distinguished based on compositional changes, thereby achieving the goal of identifying high-quality reservoirs. Carbonate rock formations can be differentiated into limestone, dolomite, and gypsum based on the changes in the content of Ca, Mg, and S elements.

[0006] The northeastern Sichuan region is mainly composed of progradational oolitic limestone with weak or undeveloped dolomitization. It generally exhibits characteristics of high Ca, low Mg, and low S. Taking YF3 as an example, the Ca content is 33.4%–37.49%, with an average of 35.96%; the Mg content is 0.303%–0.887%, with an average of 0.500%; and the S content is 0.376%–1.104%, with an average of 0.587%. Based on the variation in element content, it is classified as limestone. There is no obvious variation characteristic between different periods of oolitic limestone. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention proposes a drilling evaluation method and its application for high-quality oolitic limestone reservoirs.

[0008] In a first aspect, this invention proposes a method for evaluating high-quality reservoirs in progradational oolitic limestone during drilling, comprising the following steps:

[0009] Step 1: Elemental logging while drilling is used to collect elemental data, and the collected elemental data is processed using a data smoothing method;

[0010] Step 2: Select the dense layer at the top of the oolitic limestone as the standard layer and perform the curve morphology processing of the smoothed element data in steps 3-7.

[0011] Step 3: Select Ca and Mg elements to plot carbonate discrimination curves. Plot Ca and Mg elements on the same curve, with depth as the vertical axis and element content as the horizontal axis. The right scale represents the maximum value and the left scale represents the minimum value. Set the curves to be filled to the left, and the filling boundary is the content of another element at the same depth.

[0012] Step 4: Based on the filling effect of the two curves in Step 3, define S. Cal分叉 S Cal交会 ;

[0013] Step 5: Based on the selected standard layer, adjust the minimum and maximum values ​​of Ca and Mg elements so that the curves of Ca and Mg in the standard layer segment basically overlap.

[0014] Step 6: Select Si and Fe elements to plot sand quality discrimination curves. Both Si and Fe element curves are set to left-fill, with the filling boundary being the content of another element at the same depth. Define S... Sand分叉 S sand交会 By adjusting the curve scale, the curves for Si and Fe elements in the standard layer segment are made to basically overlap.

[0015] Step 7: Select Al and K elements to plot mud texture discrimination curves. Both Al and K element curves are set to left-fill, with the fill boundary being the content of another element at the same depth. Define S. Shale分叉 S shale交会 By adjusting the curve scale, the curves of Al and K elements in the standard layer segment are made to basically overlap.

[0016] Step 8: If the carbonate discrimination curve and at least one of the sandy or muddy discrimination curves intersects, it is determined to be a high-quality reservoir.

[0017] In a specific embodiment of the present invention, in step 1, the data smoothing method is an N-point moving average method. This method averages 2n+1 observations to obtain the processing result of the current position. The calculation formula is as follows:

[0018] E i =(A i-n +A i-n+1 +A i-n+2 +…+A i +A i+1 +A i+2 +…+A i+n ) / N

[0019] In the formula: E i The value, representing the smoothed result of logging data at a certain depth point, is %.

[0020] A i The percentage represents the raw logging data value at a certain depth point.

[0021] A i-1 For A i The original data value of the previous depth point, %;

[0022] A i+1 For A i The raw data value of the next depth point, %;

[0023] n is the number of observations;

[0024] N is the sliding window, which is numerically equal to 2n+1.

[0025] As a specific embodiment of the present invention, in step 1, the element data processing further includes eliminating the burr phenomenon of the original data, for example, by taking multiple values ​​and comparing the smoothing effect to determine the smoothing window, so as to remove curve burrs.

[0026] As a specific embodiment of the present invention, the size of the sliding window (determined by the value of N) will affect the smoothing result. The recommended value range is 3 to 10, and the general value is 5.

[0027] In a specific embodiment of the present invention, in step 2, the thickness of the standard layer is not less than 5 meters.

[0028] As a specific embodiment of the present invention, according to the actual drilling data of the work area, the lithology of the overlying oolitic limestone is generally limestone, and the top of the oolitic limestone is generally a dense layer. This dense layer is used as the standard layer for element curve morphology processing. Starting from the top of the oolitic limestone, the thickness of the selected standard layer is not less than 5 meters.

[0029] As a specific embodiment of the present invention, in steps 5, 6, and 7, the "basic overlap" includes situations where the curves of each individual have large independent fluctuations and cannot completely overlap, and where each individual independently... Cal分叉 = (0.9~1.1)S Cal Meeting.

[0030] In a specific embodiment of the present invention, Ca and Mg elements are selected as carbonate discrimination curves. Smoothed elemental logging data is used to plot the curves, with both elements plotted on the same curve. Depth is used as the ordinate, and elemental content as the abscissa, with the right scale representing the maximum value and the left scale representing the minimum value. A filling mode is set between the curves. The Mg element curve is set to left filling, with the filling boundary at the Ca element content at the same depth. The Ca element curve is also set to left filling, with the filling boundary at the Mg element content at the same depth. To make the display more prominent, different colors or patterns can be selected for filling in practice. The two curves will produce two different filling effects. When the Ca content curve is to the left of the Mg element curve, the two curves are bifurcated, and the filled portion is the bifurcation of the two curves, the area of ​​which is defined as S. Cal分叉 When the Ca content curve is to the right of the Mg element curve, the two curves intersect, and the area filled is the intersection of the two curves, defined as S. Cal交会 Based on the selected standard layer, adjust the left and right scales for Ca and Mg elements so that the curves for the two elements in the standard layer segment basically overlap. If the curves fluctuate greatly and cannot completely overlap, ensure that S... Cal分叉 ≈S Cal交会 ;

[0031] As a specific embodiment of the present invention, similarly, in step 6, Si and Fe elements are selected as sand quality discrimination curves. Smoothed elemental logging data is used to plot the curves, with both elements plotted on the same curve. Depth is used as the ordinate, and element content as the abscissa. For Fe, the right scale represents the maximum value, and the left scale represents the minimum value. For Si, the left scale represents the maximum value, and the right scale represents the minimum value. Both element curves are set to left-fill, with the filling boundary being the content of another element at the same depth. To make the display more prominent, different colors or symbols can be selected for filling. When the Si content curve is to the left of the Fe element curve, the two curves are bifurcated, and the filled portion is the bifurcation of the two curves, with its area defined as S. Sand分叉 When the Si content curve is located to the right of the Fe element curve, the area of ​​the intersection of the curves is defined as S. sand交会 By adjusting the curve scale, the two element curves in the standard layer segment are made to basically overlap, or S Sand分叉 ≈S Sand交会 ;

[0032] As a specific embodiment of the present invention, similarly, in step 7, Al and K elements are selected as mud quality discrimination curves. Smoothed element logging data is used to plot the curves, with both elements plotted on the same curve. Depth is used as the ordinate, and element content as the abscissa. For K element, the right scale represents the maximum value, and the left scale represents the minimum value. For Al element, the settings are reversed, with the left scale representing the maximum value and the right scale representing the minimum value. Both element curves are set to left-fill, with the filling boundary being the content of another element at the same depth. To make the display more prominent, different colors or symbols can be selected for filling. When the Al content curve is to the left of the K element curve, the two curves are bifurcated, and the filled portion is the bifurcation of the two curves, with its area defined as S. Shale分叉 When the Al content curve is located to the right of the K element curve, the area of ​​the intersection of the curves is defined as S. shale交会 By adjusting the curve scale, the two element curves in the standard layer segment are made to basically overlap, or S Shale分叉 ≈S Shale交会 ;

[0033] As a specific embodiment of the present invention, in step 8, the curve intersection phenomenon includes: S Cal交会 >S Cal分叉 And S Sand交会 >S Sand分叉 and / or S Shale交会 >S Shale分叉 The depth at which the curves intersect represents the top boundary depth of a high-quality reservoir.

[0034] As a specific embodiment of the present invention, in step 8, the three types of discrimination curves—carbonate, sandy, and argillaceous—are compared in the oolitic limestone section. When the carbonate discrimination curve intersects with the sandy or argillaceous discrimination curve, and at least one of the three types of curves also intersects, it is determined to be a high-quality reservoir, i.e., S. Cal交会 >S Cal分叉 And S Sand交会 >S Sand分叉 or S Shale交会 >S Shale分叉 The depth at which the curves intersect represents the top boundary depth of a high-quality reservoir. When all three types of curves intersect simultaneously, it indicates an optimal reservoir; the larger the intersection area, the better the reservoir properties.

[0035] As a specific embodiment of the present invention, in step 8, the curve intersection phenomenon further includes: when the intersection area of ​​the carbonate discrimination curves decreases, and at least one type of curve in the sandy or muddy discrimination curves shows the phenomenon of curve overlap or curve bifurcation, it is determined to be the bottom of a high-quality reservoir.

[0036] As a specific embodiment of the present invention, the curve intersection phenomenon is S Cal交会 Decrease, and S Sand交会≤S Sand分叉 and / or S Shale交会 ≤S Shale分叉 ;

[0037] The depth at which the curves overlap or bifurcate represents the bottom boundary depth of a high-quality reservoir.

[0038] In a specific embodiment of the present invention, in the oolitic limestone section, the three types of discrimination curves—carbonate, sandy, and argillaceous—are compared. When the intersection area of ​​the carbonate discrimination curve shows a decreasing trend, and at least one of the sandy or argillaceous discrimination curves shows curve overlap or bifurcation, it is determined to be the bottom of a high-quality reservoir, i.e., S. Cal交会 There is a decreasing trend, and S Sand交会 ≤S Sand分叉 or S Shale交会 ≤S Shale分叉 The depth at which the curves overlap or bifurcate represents the bottom boundary depth of a high-quality reservoir.

[0039] As a specific embodiment of the present invention, in step 8, the curve intersection phenomenon includes: dividing the oolitic beach period according to the change in the intersection area of ​​the three types of curves; when the change in the intersection area of ​​one type of curve exceeds one-third, it is determined that a new oolitic beach period has appeared, with the half-amplitude point of the curve change as the boundary for period division; the half-amplitude point refers to the position halfway between the starting point and the ending point of the curve change, such as... Figure 1 As shown.

[0040] Secondly, the drilling evaluation method for high-quality oolitic limestone reservoirs provided by this invention is applied in the fields of petroleum geology and logging.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. The evaluation method of this invention has high accuracy. Conventional electromagnetic wave induction-type resistivity measurement while drilling has an upper limit of 4000 Ω·m, and its application is limited beyond this range. By applying elemental logging technology to characterize the subtle variations in the elemental composition of oolitic limestone, it is not limited by the formation resistivity range, thus achieving the purpose of identifying high-quality reservoirs and classifying oolitic limestone phases.

[0043] 2. The evaluation method of this invention offers high cost-effectiveness. Identifying high-quality reservoirs in carbonate formations mainly relies on resistivity logging. Currently, the daily cost of resistivity logging while drilling is 40,000 to 70,000 yuan. If a single well is drilled for 20 days, the construction cost would be 800,000 to 1.4 million yuan. Using post-drilling wireline logging, the cost per well is also around 400,000 to 500,000 yuan. In contrast, the daily cost of elemental logging is less than 4,000 yuan. Based on the elemental logging method, the construction cost is less than 100,000 yuan, saving more than 300,000 yuan per well.

[0044] 3. The evaluation method of this invention has strong timeliness. Elemental logging is carried out while drilling, so it can be analyzed in real time during the drilling process. Its timeliness is basically consistent with that of logging while drilling resistivity, and is higher than that of post-drilling wireline logging. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of half-width point division in step 8 of the evaluation method of the present invention;

[0046] Figure 2 This is a drilling evaluation diagram of the progradational oolitic limestone reservoir in well F3 in Example 1 of this invention;

[0047] Figure 3 This is a drilling evaluation diagram of the progradational oolitic limestone reservoir in well F203 in Example 2 of the present invention. Detailed Implementation

[0048] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0049] Example 1

[0050] This embodiment provides a drilling evaluation method for high-quality oolitic limestone reservoirs, applied to well F3 in area Y. Specific details are as follows:

[0051] Step 1: Process the element data using an N-point moving average method, where N is 5. Plot the smoothed element data.

[0052] Step 2: Select the dense oolitic limestone at the top well depth of 6407-6412 meters as the standard layer;

[0053] Step 3: Select Ca and Mg elements to set the filling mode, such as... Figure 2 As shown, the Ca scale is set to 30-48, the Mg scale to 0-2, the Si scale to 2.4-0, the Fe scale to 0-1, the Al scale to 0.55-0, the K scale to 0-0.25, and the standard layer segment S. Cal分叉 =1.03×S Cal交会 S Sand分叉 =1.06×S Sand交会 S Shale分叉 =1.08×S Shale交会 ;

[0054] Step 4: By comparing the three types of curves (carbonate, sandy, and muddy), starting at a well depth of 6412 meters, S... Cal交会 >S Cal分叉 And S Sand交会 >S Sand分叉 The depth at which a high-quality reservoir is determined.

[0055] Step 5: When the three types of curves intersect simultaneously in two well sections at depths of 6419-6433 meters and 6437-6548 meters, it indicates a high-quality reservoir.

[0056] Step 6: Well depth 6458 meters, S Cal交会 There is a decreasing trend, and S Shale交会 ≤S Shale分叉 The depth at which a high-quality reservoir is determined.

[0057] Step 7: Divide the oolitic shoal phases according to the changes in the intersection area of ​​the three types of curves, and divide the entire well section into five phases, such as... Figure 2 As shown.

[0058] Comparing the evaluation method obtained in Example 1 with the logging curve results, the resistivity (RD, RS) of the two high-quality reservoir sections is relatively lower, indicating that the gas content of the high-quality reservoir is better. The gas logging shows that the total hydrocarbon content increases from 0.209% to 3.598%. Based on the analysis of all data, the logging evaluation results are considered reliable.

[0059] Example 2

[0060] This embodiment provides a drilling evaluation method for high-quality oolitic limestone reservoirs, applied to the F203 well project in area B. Specific details are as follows:

[0061] Step 1: Process the element data using an N-point moving average method, where N is 5. Plot the smoothed element data.

[0062] Step 2: Select the dense oolitic limestone at the top well depth of 6498-6509.5 meters as the standard layer.

[0063] Step 3: Select Ca and Mg elements to set the filling mode, such as... Figure 3 As shown, the Ca scale is set to 28-55, the Mg scale to 0-2, the Si scale to 1.4-0.2, the Fe scale to 0-1.1, the Al scale to 0.35-0.1, the K scale to 0-0.25, and the standard layer segment S. Cal分叉 =1.07×S Cal交会 S Sand分叉 =1.06×S Sand交会 S Shale分叉 =1.02×S Shale交会 ;

[0064] Step 4: By comparing the three types of curves (carbonate, sandy, and muddy), starting at a well depth of 6509.5 meters, S... Cal交会 >S Cal分叉 And S Sand交会 >S Sand分叉 S Shale交会 >S Shale分叉The depth at which a high-quality reservoir is determined.

[0065] Step 5: When the three types of curves intersect simultaneously in the well section with a depth of 6509.5-6534 meters, it indicates a high-quality reservoir.

[0066] Step 6: Well depth 6534-6566 meters, S Cal交会 =1.05×S Cal分叉 And S Sand交会 >S Sand分叉 S Shale交会 >S Shale分叉 It was determined to be a reservoir.

[0067] Step 7: Well depth 6566 meters S Cal交会 Cal分叉 This is determined as the bottom boundary depth of the reservoir.

[0068] Step 8: Divide the oolitic shoal phases according to the changes in the intersection area of ​​the three types of curves, and divide the entire well section into three phases, such as... Figure 3 As shown.

[0069] No logging was performed after the well was completed. Based on the evaluation method obtained in Example 2, a high-quality reservoir section was identified. Acidizing tests were conducted on a 24.5-meter section from 6509.5 to 6534 meters, yielding 17,000 cubic meters of gas per day, proving that the logging-while-drilling evaluation results are reliable.

[0070] Comparative Example

[0071] This comparative example provides an existing evaluation method while drilling, applied to the project in Example 2, with the following details:

[0072] Existing evaluation methods distinguish lithology by changes in elemental content. According to Ca elemental analysis, the entire well section is limestone. Combined with thin section analysis, the lithology can be further determined to be oolitic limestone. The well section is 6509.5-6566 meters long, with a total thickness of 56.5 meters. However, it is not possible to distinguish the different phases of the oolitic limestone.

[0073] Since it is impossible to distinguish between oolitic limestone of different qualities, testing needs to be conducted on the entire 56.5-meter well section, which will more than double the number of test sections and lead to a significant increase in testing costs.

[0074] ​In summary, the drilling evaluation method for high-quality oolitic limestone reservoirs of the present invention, based on elemental logging analysis, uses Ca and Mg as carbonate discrimination curves, Si and Fe as sandstone discrimination curves, and Al and K as argillaceous discrimination curves. It selects standard layers for sensitive element superposition, identifies high-quality reservoirs based on curve morphology changes, and divides oolitic limestone into stages, thus forming a drilling evaluation method for high-quality oolitic limestone reservoirs. This method can provide trajectory optimization during horizontal well construction, guide drilling operations, and improve the encounter rate of high-quality reservoirs.

[0075] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0076] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A drilling evaluation method for high-quality oolitic limestone reservoirs, characterized in that, Includes the following steps: Step 1: Elemental logging while drilling is used to collect elemental data, and the collected elemental data is processed using a data smoothing method; Step 2: Select the dense layer at the top of the oolitic limestone as the standard layer and perform the curve morphology processing of the smoothed element data in steps 3-7. Step 3: Select Ca and Mg elements to plot carbonate discrimination curves. Plot Ca and Mg elements on the same curve, with depth as the vertical axis and element content as the horizontal axis. The right scale represents the maximum value and the left scale represents the minimum value. Set the curves to be filled to the left, and the filling boundary is the content of another element at the same depth. Step 4: Based on the filling effect of the two curves in Step 3, define S. Cal分叉 S Cal交会 ; Step 5: Based on the selected standard layer, adjust the minimum and maximum values ​​of Ca and Mg elements so that the curves of Ca and Mg in the standard layer segment basically overlap. Step 6: Select Si and Fe elements to plot sand quality discrimination curves. Both Si and Fe element curves are set to left-fill, with the filling boundary being the content of another element at the same depth. Define S... Sand分叉 S sand交会 By adjusting the curve scale, the curves for Si and Fe elements in the standard layer segment are made to basically overlap. Step 7: Select Al and K elements to plot mud texture discrimination curves. Both Al and K element curves are set to left-fill, with the fill boundary being the content of another element at the same depth. Define S. Shale分叉 S shale交会 By adjusting the curve scale, the curves of Al and K elements in the standard layer segment are made to basically overlap. Step 8: If the carbonate discrimination curve and at least one of the sandy or muddy discrimination curves intersects, it is determined to be a high-quality reservoir.

2. The evaluation method according to claim 1, characterized in that, In step 1, the data smoothing method is the N-point moving average method. This method averages 2n+1 observations to obtain the processing result for the current position. The calculation formula is as follows: E i = (A i-n +A i-n+1 +A i-n+2 +…+A i +A i+1 +A i+2 +…+A i+n ) / N In the formula: E i The value of the smoothed logging data at a certain depth point is % A i The raw logging data value at a certain depth point, % A i-1 For A i The original data value of the previous depth point, % A i+1 For A i The raw data value of the next depth point, % n is the number of observations; N is the sliding window, which is numerically equal to 2n+1.

3. The evaluation method according to claim 1 or 2, characterized in that, Step 1, processing the collected element data, also includes eliminating spikes in the original data.

4. The evaluation method according to claim 3, characterized in that, In step 1, the smoothing window is determined by taking multiple values ​​and comparing the smoothing effect in order to remove curve burrs.

5. The evaluation method according to any one of claims 1, 2, and 4, characterized in that, In step 2, the thickness of the standard layer is not less than 5 meters.

6. The evaluation method according to any one of claims 1, 2, and 4, characterized in that, In steps 5, 6, and 7, the "basic overlap" includes situations where the curves of each individual curve have large fluctuations and cannot completely overlap, and where each individual curve independently... Cal分叉 =(0.9~1.1)S Cal交会 .

7. The evaluation method according to any one of claims 1, 2, and 4, characterized in that, In step 8, the curve intersection phenomenon includes: S Cal交会 >S Cal分叉 And S Sand交会 >S Sand分叉 and / or S Shale交会 >S Shale分叉 ; The depth at which the curves intersect represents the top boundary depth of a high-quality reservoir.

8. The evaluation method according to any one of claims 1, 2, and 4, characterized in that, In step 8, the curve intersection phenomenon further includes: when the intersection area of ​​the carbonate discrimination curves decreases, and at least one type of curve in the sandy or muddy discrimination curves shows curve overlap or curve bifurcation, it is determined to be the bottom of a high-quality reservoir.

9. The evaluation method according to claim 8, characterized in that, The curve intersection phenomenon is S Cal交会 Decrease, and S Sand交会 ≤S Sand分叉 and / or S Shale交会 ≤S Shale分叉 ; The depth at which the curves overlap or bifurcate represents the bottom boundary depth of a high-quality reservoir.

10. The evaluation method according to any one of claims 1, 2, 4 and 9, characterized in that, In step 8, the curve intersection phenomenon includes: dividing the oolitic beach period according to the change of the intersection area of ​​the three types of curves. When the change of the intersection area of ​​one type of curve exceeds one-third, it is determined that a new oolitic beach period has appeared. The half-amplitude point of the curve change is used as the boundary for dividing the period. The half-amplitude point refers to the position halfway between the starting point and the ending point of the change when the curve changes.

11. The application of the drilling evaluation method for high-quality oolitic limestone reservoirs according to any one of claims 1-10 in the fields of petroleum geology and logging.

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